add multi targeting frameworks in the same project for net 4.5 through net 7.0 and net standard 2.0

src/UglyToad.PdfPig/AcroForms/AcroFormFactory.cs

@@ -229,7 +229,7 @@
 
         private AcroFieldBase GetChoiceField(DictionaryToken fieldDictionary, NameToken fieldType, uint fieldFlags, AcroFieldCommonInformation information)
         {
-            var selectedOptions = Array.Empty<string>();
+            var selectedOptions = EmptyArray<string>.Instance;
             if (fieldDictionary.TryGet(NameToken.V, out var valueToken))
             {
                 if (DirectObjectFinder.TryGet(valueToken, tokenScanner, out StringToken valueString))

src/UglyToad.PdfPig/CrossReference/TrailerDictionary.cs

@@ -91,7 +91,7 @@
             }
             else
             {
-                Identifier = Array.Empty<string>();
+                Identifier = EmptyArray<string>.Instance;
             }
 
             if (dictionary.TryGet(NameToken.Encrypt, out var encryptionToken))

src/UglyToad.PdfPig/Fonts/AdobeStylePrivateDictionary.cs

@@ -2,6 +2,7 @@
 {
     using System;
     using System.Collections.Generic;
+    using Util;
     using Util.JetBrains.Annotations;
 
     /// <summary>
@@ -150,17 +151,17 @@
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            BlueValues = builder.BlueValues ?? Array.Empty<int>();
+            BlueValues = builder.BlueValues ?? EmptyArray<int>.Instance;
-            OtherBlues = builder.OtherBlues ?? Array.Empty<int>();
+            OtherBlues = builder.OtherBlues ?? EmptyArray<int>.Instance;
-            FamilyBlues = builder.FamilyBlues ?? Array.Empty<int>();
+            FamilyBlues = builder.FamilyBlues ?? EmptyArray<int>.Instance;
-            FamilyOtherBlues = builder.FamilyOtherBlues ?? Array.Empty<int>();
+            FamilyOtherBlues = builder.FamilyOtherBlues ?? EmptyArray<int>.Instance;
             BlueScale = builder.BlueScale ?? DefaultBlueScale;
             BlueFuzz = builder.BlueFuzz ?? DefaultBlueFuzz;
             BlueShift = builder.BlueShift ?? DefaultBlueShift;
             StandardHorizontalWidth = builder.StandardHorizontalWidth;
             StandardVerticalWidth = builder.StandardVerticalWidth;
-            StemSnapHorizontalWidths = builder.StemSnapHorizontalWidths ?? Array.Empty<decimal>();
+            StemSnapHorizontalWidths = builder.StemSnapHorizontalWidths ?? EmptyArray<decimal>.Instance;
-            StemSnapVerticalWidths = builder.StemSnapVerticalWidths ?? Array.Empty<decimal>();
+            StemSnapVerticalWidths = builder.StemSnapVerticalWidths ?? EmptyArray<decimal>.Instance;
             ForceBold = builder.ForceBold ?? false;
             LanguageGroup = builder.LanguageGroup ?? DefaultLanguageGroup;
             ExpansionFactor = builder.ExpansionFactor ?? DefaultExpansionFactor;

src/UglyToad.PdfPig/Fonts/CompactFontFormat/CompactFontFormatIndex.cs

@@ -1,8 +1,8 @@
 namespace UglyToad.PdfPig.Fonts.CompactFontFormat
 {
-    using System;
     using System.Collections;
     using System.Collections.Generic;
+    using Util;
     using Util.JetBrains.Annotations;
 
     internal class CompactFontFormatIndex : IReadOnlyList<IReadOnlyList<byte>>
@@ -18,7 +18,7 @@
 
         public CompactFontFormatIndex(byte[][] bytes)
         {
-            this.bytes = bytes ?? Array.Empty<IReadOnlyList<byte>>();
+            this.bytes = bytes ?? EmptyArray<IReadOnlyList<byte>>.Instance;
         }
         
         public IEnumerator<IReadOnlyList<byte>> GetEnumerator()

src/UglyToad.PdfPig/Fonts/CompactFontFormat/CompactFontFormatIndexReader.cs

@@ -2,6 +2,8 @@
 
 namespace UglyToad.PdfPig.Fonts.CompactFontFormat
 {
+    using Util;
+
     internal class CompactFontFormatIndexReader
     {
         public CompactFontFormatIndex ReadDictionaryData(CompactFontFormatData data)
@@ -43,7 +45,7 @@ namespace UglyToad.PdfPig.Fonts.CompactFontFormat
 
             if (count == 0)
             {
-                return Array.Empty<int>();
+                return EmptyArray<int>.Instance;
             }
 
             var offsetSize = data.ReadOffsize();

src/UglyToad.PdfPig/Fonts/SystemFonts/ISystemFontLister.cs

@@ -0,0 +1,9 @@
+namespace UglyToad.PdfPig.Fonts.SystemFonts
+{
+    using System.Collections.Generic;
+
+    internal interface ISystemFontLister
+    {
+        IEnumerable<SystemFontRecord> GetAllFonts();
+    }
+}

src/UglyToad.PdfPig/Fonts/SystemFonts/LinuxSystemFontLister.cs

@@ -0,0 +1,68 @@
+namespace UglyToad.PdfPig.Fonts.SystemFonts
+{
+    using System;
+    using System.Collections.Generic;
+    using System.IO;
+
+    internal class LinuxSystemFontLister : ISystemFontLister
+    {
+        public IEnumerable<SystemFontRecord> GetAllFonts()
+        {
+            var directories = new List<string>
+            {
+                "/usr/local/fonts", // local
+                "/usr/local/share/fonts", // local shared
+                "/usr/share/fonts", // system
+                "/usr/X11R6/lib/X11/fonts" // X
+            };
+
+            try
+            {
+                var folder = Environment.GetEnvironmentVariable("$HOME");
+
+                if (!string.IsNullOrWhiteSpace(folder))
+                {
+                    directories.Add($"{folder}/.fonts");
+                }
+            }
+            catch
+            {
+                // ignored
+            }
+
+            foreach (var directory in directories)
+            {
+                try
+                {
+                    if (!Directory.Exists(directory))
+                    {
+                        continue;
+                    }
+                }
+                catch
+                {
+                    continue;
+                }
+
+                string[] files;
+
+                try
+                {
+                    files = Directory.GetFiles(directory);
+                }
+                catch
+                {
+                    continue;
+                }
+
+                foreach (var file in files)
+                {
+                    if (SystemFontRecord.TryCreate(file, out var record))
+                    {
+                        yield return record;
+                    }
+                }
+            }
+        }
+    }
+}

src/UglyToad.PdfPig/Fonts/SystemFonts/MacSystemFontLister.cs

@@ -0,0 +1,67 @@
+namespace UglyToad.PdfPig.Fonts.SystemFonts
+{
+    using System;
+    using System.Collections.Generic;
+    using System.IO;
+
+    internal class MacSystemFontLister : ISystemFontLister
+    {
+        public IEnumerable<SystemFontRecord> GetAllFonts()
+        {
+            var directories = new List<string>
+            {
+                "/Library/Fonts/", // local
+                "/System/Library/Fonts/", // system
+                "/Network/Library/Fonts/" // network
+            };
+
+            try
+            {
+                var folder = Environment.GetEnvironmentVariable("$HOME");
+
+                if (!string.IsNullOrWhiteSpace(folder))
+                {
+                    directories.Add($"{folder}/Library/Fonts");
+                }
+            }
+            catch
+            {
+                // ignored
+            }
+
+            foreach (var directory in directories)
+            {
+                try
+                {
+                    if (!Directory.Exists(directory))
+                    {
+                        continue;
+                    }
+                }
+                catch
+                {
+                    continue;
+                }
+
+                string[] files;
+
+                try
+                {
+                    files = Directory.GetFiles(directory);
+                }
+                catch
+                {
+                    continue;
+                }
+
+                foreach (var file in files)
+                {
+                    if (SystemFontRecord.TryCreate(file, out var record))
+                    {
+                        yield return record;
+                    }
+                }
+            }
+        }
+    }
+}

src/UglyToad.PdfPig/Fonts/SystemFonts/SystemFontFinder.cs

@@ -19,7 +19,9 @@
         public SystemFontFinder(TrueTypeFontParser trueTypeFontParser)
         {
             this.trueTypeFontParser = trueTypeFontParser;
+
             ISystemFontLister lister;
+#if NETSTANDARD2_0
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
             {
                 lister = new WindowsSystemFontLister();
@@ -36,6 +38,9 @@
             {
                 throw new NotSupportedException($"Unsupported operating system: {RuntimeInformation.OSDescription}.");
             }
+#else 
+            lister = new WindowsSystemFontLister();
+#endif
 
             availableFonts = new Lazy<IReadOnlyList<SystemFontRecord>>(() => lister.GetAllFonts().ToList());
         }
@@ -75,230 +80,4 @@
             return null;
         }
     }
-
-    internal interface ISystemFontLister
-    {
-        IEnumerable<SystemFontRecord> GetAllFonts();
-    }
-
-    internal class WindowsSystemFontLister : ISystemFontLister
-    {
-        public IEnumerable<SystemFontRecord> GetAllFonts()
-        {
-            // TODO: Could use System.Drawing InstalledFontCollection to do this?
-
-            var winDir = Environment.GetFolderPath(Environment.SpecialFolder.Windows);
-
-            var fonts = Path.Combine(winDir, "Fonts");
-
-            if (Directory.Exists(fonts))
-            {
-                var files = Directory.GetFiles(fonts);
-
-                foreach (var file in files)
-                {
-                    if (SystemFontRecord.TryCreate(file, out var record))
-                    {
-                        yield return record;
-                    }
-                }
-            }
-
-            var psFonts = Path.Combine(winDir, "PSFonts");
-
-            if (Directory.Exists(psFonts))
-            {
-                var files = Directory.GetFiles(fonts);
-
-                foreach (var file in files)
-                {
-                    if (SystemFontRecord.TryCreate(file, out var record))
-                    {
-                        yield return record;
-                    }
-                }
-            }
-        }
-    }
-
-    internal class LinuxSystemFontLister : ISystemFontLister
-    {
-        public IEnumerable<SystemFontRecord> GetAllFonts()
-        {
-            var directories = new List<string>
-            {
-                "/usr/local/fonts", // local
-                "/usr/local/share/fonts", // local shared
-                "/usr/share/fonts", // system
-                "/usr/X11R6/lib/X11/fonts" // X
-            };
-
-            try
-            {
-                var folder = Environment.GetEnvironmentVariable("$HOME");
-
-                if (!string.IsNullOrWhiteSpace(folder))
-                {
-                    directories.Add($"{folder}/.fonts");
-                }
-            }
-            catch
-            {
-                // ignored
-            }
-
-            foreach (var directory in directories)
-            {
-                try
-                {
-                    if (!Directory.Exists(directory))
-                    {
-                        continue;
-                    }
-                }
-                catch
-                {
-                    continue;
-                }
-
-                string[] files;
-
-                try
-                {
-                    files = Directory.GetFiles(directory);
-                }
-                catch
-                {
-                    continue;
-                }
-
-                foreach (var file in files)
-                {
-                    if (SystemFontRecord.TryCreate(file, out var record))
-                    {
-                        yield return record;
-                    }
-                }
-            }
-        }
-    }
-
-    internal class MacSystemFontLister : ISystemFontLister
-    {
-        public IEnumerable<SystemFontRecord> GetAllFonts()
-        {
-            var directories = new List<string>
-            {
-                "/Library/Fonts/", // local
-                "/System/Library/Fonts/", // system
-                "/Network/Library/Fonts/" // network
-            };
-
-            try
-            {
-                var folder = Environment.GetEnvironmentVariable("$HOME");
-
-                if (!string.IsNullOrWhiteSpace(folder))
-                {
-                    directories.Add($"{folder}/Library/Fonts");
-                }
-            }
-            catch
-            {
-                // ignored
-            }
-
-            foreach (var directory in directories)
-            {
-                try
-                {
-                    if (!Directory.Exists(directory))
-                    {
-                        continue;
-                    }
-                }
-                catch
-                {
-                    continue;
-                }
-
-                string[] files;
-
-                try
-                {
-                    files = Directory.GetFiles(directory);
-                }
-                catch
-                {
-                    continue;
-                }
-
-                foreach (var file in files)
-                {
-                    if (SystemFontRecord.TryCreate(file, out var record))
-                    {
-                        yield return record;
-                    }
-                }
-            }
-        }
-    }
-
-    internal struct SystemFontRecord
-    {
-        public string Path { get; }
-
-        public SystemFontType Type { get; }
-
-        public SystemFontRecord(string path, SystemFontType type)
-        {
-            Path = path ?? throw new ArgumentNullException(nameof(path));
-            Type = type;
-        }
-
-        public static bool TryCreate(string path, out SystemFontRecord type)
-        {
-            type = default(SystemFontRecord);
-
-            SystemFontType fontType;
-            if (path.EndsWith(".ttf"))
-            {
-                fontType = SystemFontType.TrueType;
-            }
-            else if (path.EndsWith(".otf"))
-            {
-                fontType = SystemFontType.OpenType;
-            }
-            else if (path.EndsWith(".ttc"))
-            {
-                fontType = SystemFontType.TrueTypeCollection;
-            }
-            else if (path.EndsWith(".otc"))
-            {
-                fontType = SystemFontType.OpenTypeCollection;
-            }
-            else if (path.EndsWith(".pfb"))
-            {
-                fontType = SystemFontType.Type1;
-            }
-            else
-            {
-                return false;
-            }
-
-            type = new SystemFontRecord(path, fontType);
-
-            return true;
-        }
-    }
-
-    internal enum SystemFontType
-    {
-        Unknown = 0,
-        TrueType = 1,
-        OpenType = 2,
-        Type1 = 3,
-        TrueTypeCollection = 4,
-        OpenTypeCollection = 5
-    }
 }

src/UglyToad.PdfPig/Fonts/SystemFonts/SystemFontRecord.cs

@@ -0,0 +1,52 @@
+namespace UglyToad.PdfPig.Fonts.SystemFonts
+{
+    using System;
+
+    internal struct SystemFontRecord
+    {
+        public string Path { get; }
+
+        public SystemFontType Type { get; }
+
+        public SystemFontRecord(string path, SystemFontType type)
+        {
+            Path = path ?? throw new ArgumentNullException(nameof(path));
+            Type = type;
+        }
+
+        public static bool TryCreate(string path, out SystemFontRecord type)
+        {
+            type = default(SystemFontRecord);
+
+            SystemFontType fontType;
+            if (path.EndsWith(".ttf"))
+            {
+                fontType = SystemFontType.TrueType;
+            }
+            else if (path.EndsWith(".otf"))
+            {
+                fontType = SystemFontType.OpenType;
+            }
+            else if (path.EndsWith(".ttc"))
+            {
+                fontType = SystemFontType.TrueTypeCollection;
+            }
+            else if (path.EndsWith(".otc"))
+            {
+                fontType = SystemFontType.OpenTypeCollection;
+            }
+            else if (path.EndsWith(".pfb"))
+            {
+                fontType = SystemFontType.Type1;
+            }
+            else
+            {
+                return false;
+            }
+
+            type = new SystemFontRecord(path, fontType);
+
+            return true;
+        }
+    }
+}

src/UglyToad.PdfPig/Fonts/SystemFonts/SystemFontType.cs

@@ -0,0 +1,12 @@
+namespace UglyToad.PdfPig.Fonts.SystemFonts
+{
+    internal enum SystemFontType
+    {
+        Unknown = 0,
+        TrueType = 1,
+        OpenType = 2,
+        Type1 = 3,
+        TrueTypeCollection = 4,
+        OpenTypeCollection = 5
+    }
+}

src/UglyToad.PdfPig/Fonts/SystemFonts/WindowsSystemFontLister.cs

@@ -0,0 +1,46 @@
+namespace UglyToad.PdfPig.Fonts.SystemFonts
+{
+    using System;
+    using System.Collections.Generic;
+    using System.IO;
+
+    internal class WindowsSystemFontLister : ISystemFontLister
+    {
+        public IEnumerable<SystemFontRecord> GetAllFonts()
+        {
+            // TODO: Could use System.Drawing InstalledFontCollection to do this?
+
+            var winDir = Environment.GetFolderPath(Environment.SpecialFolder.Windows);
+
+            var fonts = Path.Combine(winDir, "Fonts");
+
+            if (Directory.Exists(fonts))
+            {
+                var files = Directory.GetFiles(fonts);
+
+                foreach (var file in files)
+                {
+                    if (SystemFontRecord.TryCreate(file, out var record))
+                    {
+                        yield return record;
+                    }
+                }
+            }
+
+            var psFonts = Path.Combine(winDir, "PSFonts");
+
+            if (Directory.Exists(psFonts))
+            {
+                var files = Directory.GetFiles(fonts);
+
+                foreach (var file in files)
+                {
+                    if (SystemFontRecord.TryCreate(file, out var record))
+                    {
+                        yield return record;
+                    }
+                }
+            }
+        }
+    }
+}

src/UglyToad.PdfPig/UglyToad.PdfPig.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net45;net451;net452;net46;net461;net462;net47</TargetFrameworks>
     <PackageId>PdfPig</PackageId>
     <DebugType>full</DebugType>
     <Authors>UglyToad</Authors>
@@ -48,4 +48,14 @@
     </PackageReference>
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)'=='net45' 
+             OR '$(TargetFramework)'=='net451' 
+             OR '$(TargetFramework)'=='net452' 
+             OR '$(TargetFramework)'=='net46' 
+             OR '$(TargetFramework)'=='net461' 
+             OR '$(TargetFramework)'=='net462' 
+             OR '$(TargetFramework)'=='net47'">
+    <PackageReference Include="System.ValueTuple" Version="4.5.0" />    
+  </ItemGroup>
+  
 </Project>

src/UglyToad.PdfPig/Util/EmptyArray.cs

@@ -0,0 +1,13 @@
+namespace UglyToad.PdfPig.Util
+{
+    /// <summary>
+    /// NET 4.5 compatible Array.Empty.
+    /// </summary>
+    internal static class EmptyArray<T>
+    {
+        /// <summary>
+        /// An empty array.
+        /// </summary>
+        public static T[] Instance { get; } = new T[0];
+    }
+}